Alternating-current arc-lamp



3 Sheets-Sheet 1.

(No Model.)

B. R. KNOWLES. ALTERNATING CURRENT ARC LAMP.

Patented Mar. 2,1897.

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3 Sheets-Sheet 2v (No Model.)

B. R. KNOWLES.

ALTERNATING CURRENT ARC LAMP.

,864. Patented Mar. 2, 1897 WITNESSES:

l l l UNITED STATES PATENT OFFICE.

EDWARD R. KNOXVLES, OF BROOKLYN, NEXV YORK.

ALTERNATlNG-CURRENT ARC-LAM P.

SPECIFICATION forming part of Letters Patent No. 577,864, dated March 2,1897.

Application filed August 19,1896. Serial No. 608,181. (No model.)

T0 at whom it may concern:

Be it known that I, EDWARD R. KNowLEs, a citizen of the United States,residing at Brooklyn, in the county of Kings and State of New York, haveinvented certain new and useful Improvements in Alternating-CurrentArc-Lamps, of which the following is a full, clear, and exactdescription.

This invention relates to electric-arc lamps, the main feature of whichhas special reference to alternating-current lamps.

The primary object is to furnish a lamp which will establish the arewhen the current is turned on without the preliminary chattering of thecarbons which usually takes place in this type of lamp. The cause ofthis chattering is the mere fact that the current passing through thelamp is alternating in character. An alternating current rises and fallsbetween zero and maximum potential with great frequency, so thata singleimpulse does not last longenough to heat up the abutting ends of thecarbons and the intervening atmosphere sufficiently to produce a stablearc. The passage of a number of impulses, however, finally heats thecarbons and the atmosphere between them, so that the current will bridgethe arc-gap and flow with regularity. In the meantime the carbons hammertogether and cause the chattering. If, when the current is first turnedon, it is permitted to flow through the carbons for a short space oftime before they are separated, and then they are separated slowly, thearc will be formed at once and maintained constant without anychattering or hammering of the carbons, because in the interval of timereferred to the carbons become heated and an atmosphere adapted to carryan arc has been formed.

The principal feature of myinvention herein described is the meanswhereby the carbons are held in contact for a short period of timeimmediately after the current is turned on for the purpose referred to.

The invention also embodies other features of minor importance, butwhich taken together comprise a very practical and successful arc-lamp.

In the accompanying drawings, Figure 1 is aview of the lamp mechanismsomewhat conventionally illustrated. Fig. 2 is a view of the completelamp on a small scale and partially in section. Fig. 3 is a section ofthe lamp-magnet. Fig. 4 isadetail of the globesustaining device. Figs. 5and 6 are respec tively a side elevation and plan of the lamprheostat.Fig. 7 is a side elevation, partially in section, of the lowercarbonholder and its connecting parts; and Figs. 8 and 9 are details of theholder itself.

Referring to Fig. 1, a is a frame supporting the bottom of thelamp-case, but insulated therefrom in the usual manner.

I) is a second frame consisting of two side pieces connected bycross-rods of the same general construction as is commonly used in lampsof this character. This frame is pivoted to the main frame at the pointI). In it is mounted a train of gear having at one end the pinion 5which engages with a rack in the carbon-rod, and at the other end an escapement-wheel which is controlled by a verge b and an oscillatingweight b Said weight is of the general shape of the figure 8, stampedout of sheet metal. The periphery of the ring at one end bears against adelicate spring 0, fixed at c and having a curved end 0 which impingesagainst the edge of the ring. This spring acts as a brake or detent toprevent the oscillation of the weight and retard the gearing. By makingthis detent yielding the train is not stopped too suddenly and itsaction improves the operation of the lamp. The downward movement offrame I) is limited by pin 1).

The upper-carbon rod is represented by d and is provided with a rack d,before referred to. A single magnet E is used to strike the arc andmaintain the same. The magnet is of the solenoid type and is providedwith a dash-pot 6, attached centrally below it and forming an extensionof the passage through the coil.

e is the core, which in this instance is hollow and pivotally suspendedat its upper end upon a rod 6 which passes entirely through it and intothe dash-pot, where it carries a piston 6 The opening in the core islarger than the rod and permits of slight lateral movement of the coreto prevent binding as it moves in and out of the magnet. The upper endof rod 6 is hung at one extremity of a lever f, pivoted near its middlepoint to a bracket g. The opposite end of lever f is provided with aweight f or an equivalent spring. The lever connects with the swingingframe d by a chain, cord, or other flexible device it. This may beadjustable in length in any preferred way, the means here shown being anotched arm f secured to the lever 1, which by shifting the end of thechain into one or the other notches changes its position relative to thepivot of the lever f, and consequently the effective length of theconnector 7L.

One side of the main circuit is connected with the brush 1', which bearsconstantly against the upper-carbon rod. The main circuit then leadsthrough said red, the upper carbon, and the lower carbon, and thence tothe other side of the main circuitj. The magnet E is in a shunt to theare, being connected in a circuit 7t, leading from a point L to a cutoutspring 0. This spring is mounted upon a block of insulating material andbears at its free end normally against the side of the carbon-rod. Thecarbon-rod terminates at the top in a cone 1) of insulating material. Atthe base of the cone there is formed a small notch that stands in thepath of the end of the spring. "When the rod is fed downward to nearlythe full limit, the spring enters the notch, and the fin al movement ofthe rod puts the spring under slight tension,which eventually causes itto leave the notch and spring against the cone of insulating materialabove and thus open the shunt-circuit. Nothing is regarded as new inthis cut-out except the conical point on the rod, which, whether it beof insulating material or not, permits the rod to pass freely upwardthrough the lamp and past the cut-out spring whenever it has beenremoved for cleaning or repairs.

The operation of the lamp is as follows: The carbons are normallyseparated, in which position they are held by the weight f, the core ofthe magnet being elevated and the flexible connector 7L being straightor under tension. Then the current is first put through the lamp, themagnet gets all of it and pulls down its core 2, the movement beingcomparatively slow, due to the action of the dash-pot. The partscontinue to lower until the frame I) strikes the pin Z), at which momentthe oscillating weight If is released from the detent c, and the gearingthus being free commences to rotate under the weight of the carbon-rod.The core 6 meanwhile continues to lower until the carbons come together,at which time a considerable slack has been made in the flexibleconnector h. The moment the carbons touch the full current flows throughthem and heats up the abutting surfaces. The magnet being deenergizedthe moment the carbons touch, releases its core and permits the weight fto again withdraw it and straighten out the slacken ed connector h. Thislatter requires an appreciable amount of time, during which the carbonsbecome heated. This upward movement of the core and the straightening ofthe connector is gradual on account of the action of the dashpot, andwhen finally the frame I) commences to rise it will do so at adeliberate speed. The moment the frame I) moves the gearing be comeslocked by contact between the weight Zr and detent c, and the furthermovement of the frame determines the length of the arc. The increase ofresistance of the are causes more current to flow through the shunt,which again lowers frame 7) sufficiently to allow the gearing to rotateand feed the upper carbon downward. In this operation the connector 7Lis not materially slacken ed, because the moment the frame strikes thepin Z) the gearing is released and the resistance is altered. lVhileburning, the frame Z1 will practically be floating immediately above thepin 1).

teferring now to Figs. 2, 5, and (5, showing the lamp-rheostat, it willbe seen that the coils of resistance-wire q are arranged verticallybetween two circular rows of insulators q, the insulators being securedto rings The insulators above and below are staggered in position, sothat the coils standing between them will occupy a slightly-inclinedposition. This is true of all the coils except two, those shownimmediately in front in Figs. 5 and (3. These two are parallel and ametallic clip 0' is arranged to embrace both of them and maintain itselfin any position thereon by friction. By adjusting this clip at any pointin the length of the coils the resistance of the lamp may be altered.

Another feature of my lamp is the means for supporting the lamp-globe.The wirenetting s is hooked over the upper edges of the globe, as shownin Fig. 2, and is secured to the rim of a metal cup '6 at the lower end,in which the lower end of the globe rests. The weight of the globe issupported by two springs a, attached to the upper edge of the nettingand carrying rings a, which embrace the side rods a of the lamp. Therings are adapted to pass over hooks it, fixed to the under side of thelamp-casing, and thus the globe is flexibly supported and is not liableto become broken by sudden jars or thrusts upon the lamp. In trimmingthe lamp the globe is lowered by removing the rings from the hooks andallowing them to slide downward upon the rods until they are caught bythe cross piece carrying the lower -carbon holder. Byhooking the upperedge of the n et over the edge of the globe and then drawing down andsecuring the lower edge to the cup I provide a simple means for applyingthe net. The cup '6 at the lower end of the globe is conical in shapeand is provided with an opening at the apex, into which a plug '6 on theend of a stem 15 projects. The plug normally closes the hole in the cupand prevents particles of carbon from falling, while at the same time itfurnishes a passage for removing said can bcn particles when the globeis lowered for trimming and cleaning the lamp. The lower carbon holderconsists of the plate 7;, hav ing an angular seat for the carbon andside notches v, formed integrally with a disk t IIO i and a bolt 12*,and a small metal frame 10,

adapted to embrace the carbon and the plate o, occupying the notches '0in the latter and carrying a thumb-screw for pressing the carbon betweenthe plate and one side of the frame. Bolt 02 passes through a largeopening in the cross-piece connecting the lower ends of the side rods,and is insulated therefrom by means of non-conducting bushings o Theseare made smaller than the opening into which they pass to permit ofslight lateral adjustment of the carbon. The hole and bushings are heldin place by a nut 12 which also clamps the conducting wire j. The stem tprojects from aloop i formed integrally with the cross-piece.

Having thus described my invention, I claim- 1. The method of startingan alternating current arc-lamp in operation, which consists in holdingthe carbons in contact after the current is turned on, long enough toallow the carbons to become heated sufficiently to maintain the normalarc and then slowly separating the carbons to establish the are.

2. An arc-starting mechanism for alternatin g-current arc-lamps,comprising the combination of means for holding the carbons in contactfor a sufficient time to heat the carbons to maintain the normal arc,with means for thereafter slowly separating the carbons to establish theare.

3. An arc-starting mechanism for alternating-current arc-lamps in whichthe carbons are normally separated, comprising the combination of meansfor contacting the carbons, means for thereafter holding the carbons incontact for a sufficient time to heat the carbons to maintain the normalarc, and means for thereafter slowly separating the carbons to establishthe arc.

4. In an arc-lamp, the combination of an arc-striking magnet, acarbon-rod, a swinging frame carrying a train of gearing in engagementwith said rod, a stop limiting the movement of the frame, a pivotedlever to which the armature of the magnet is attached, and a flexibleconnection between the lever and the swinging frame whereby the formermay move after the latter is held by its stop, substantially as and forthe purpose set forth.

5. In an arc-lamp, a train of gearing controlled by an escapement, thelatter having an oscillating weight provided with a rounded surface andthe gearing being mounted in a swingingframe, in combination with ayielding detent for said weight, the detent having a correspondingrounded surface, substantially as described.

6. In an arc-lamp, the combination with the frame, of a globe-holderconsisting of a wirenetting embracing the globe and springs c011-necting the netting with the lamp-frame, substantially as described.

7. In an arc-lamp, the combination with the frame, of a globe-holderconsisting of awirenetting embracing the globe and springs connectingthe netting with the lamp-frame, said springs having attached to themrings which embrace the side rods of the lamp and which normally engagewith hooks on the lampframe, for the purpose set forth.

8. In an arc-lamp, the combination of the globe and a net embracing thesame, said net being secured at its upper edge by hooks passing over theupper edge of the globe, as set forth.

In testimony whereof I subscribe my signature in presence of twowitnesses.

EDWARD R. KNOWLES.

l Vitnesses:

FRANK S. OBER, HARRY BAILEY.

